1. Field of the Invention
The present invention generally relates to a method and apparatus for transmitting and receiving information about interference between adjacent cells (hereinafter, referred to as inter-cell interference information) in a communication system.
2. Description of the Related Art
In a communication system, interference between adjacent cells has a significant influence on the transmission efficiency of the cells. In particular, as a User Equipment (UE), also known as a terminal and a Mobile Station (MS), located in an edge region of a certain cell may receive a strong (or high-power) interference signal from adjacent cell(s), its transmission capacity may be limited more significantly by the interference signal rather than by noise. Studies have been conducted on a method of reducing inter-cell interference based on a randomization technique in which cells transmit signals with codes in different patterns independently. Recently, however, in order to more effectively minimize inter-cell interference, much research has been conducted on an interference avoidance scheme that reduces interference signals by transmitting and receiving information about the interference of pertinent adjacent cells between a serving cell and its adjacent cell.
A general interference avoidance scheme requires, first, a process of transmitting and receiving information about interference between adjacent cells. Specifically, when a serving cell allocates an arbitrary Up-Link (UL) resource to a UE located in its edge region, the UE may receive interference signals from adjacent cells when transmitting signals with the allocated UL resource. Therefore, the serving cell transmits information indicating that the UL resource allocated to the UE is sensitive or susceptible to an interference signal to each of its adjacent cells.
As described above, each cell transmits information about an interference signal regarding a certain resource to its adjacent cells, and, upon receiving the interference signal information, a cell reflects the received interference signal information during resource allocation thereby reducing inter-cell interference. Although the interference signal information may be represented by various forms, Relative Narrowband Transmit Power (RNTP) for a Down-Link (DL) and High Interference Indicator (HII) for a UL are now under discussion and have been defined in the Long-Term Evolution (LTE) standard. The purpose of RNTP and Hips to designate a low transmit power and a high interference for a specific resource on a cell-by-cell basis, respectively. Additionally, an Interference Overload Indicator (IOI) indicating a strong-interference situation has been defined for a UL.
Among the interference signal information, an HII generally indicates a level, i.e., High Interference Sensitivity (HIS), of an interference signal received from an adjacent cell and sensed by a UE when a serving cell allocates a specific resource to the UE located in an edge region of its service region (or coverage). Also, the HII implicitly indicates a level, i.e., High Interference Transmission (HIT), of an interference signal that the UE transmits to the adjacent cell. This is so because of the high correlation between interference signals from a serving cell and its adjacent cell.
However, an HIS and an HIT of a serving cell may have different values according to the location of a UE located in its adjacent cell. However, if the HII is set to simultaneously represent an HIS and an HIT of a serving cell as is conventionally done, efficiency of resource allocation may be degraded.